Need help dating Boye crochet hooks

[jenjen7260]

 I was gifted a set of three Boye aluminum crochet hooks that came from the store Ben Franklin. I know Ben Franklin went out of business before the 2000s so I figure they’re at least from the 90s. I’m just not sure when they made the switch from the letter sizing to using mm. I’ve searched a bunch of websites but have come up with nothing. I would add pictures of them but i don’t think I can add photos on here. If anyone can help please let me know. Thanks!

[Granny Square]

Welcome to the 'ville!  I am pretty sure I ran into a website that had that information, IIRC they 'dated' the hook by the font style of the word Boye.

...found it!  https://crochetistheway.blogspot.com/2015/12/hooks-with-history-boye.html

I can tell you that the plastic yarn size hooks were multi-sized in 1970, which is when I learned to crochet - but were not marked in mm then, it was old size and new size.  Mine are a little worn, but looking at one it says "F same as 3 or 4 USA", another "G same as 5 USA".  The numbers are not millimeters, but I suspect they are the US knitting needle number sizing system -- if I stick the back end of the G hook in my needle sizing tool, which is also marked with crochet hook sizes, the same hole is G for the hook and size 5 for the needle.